I am extracting metadata from mp4 files and found some keys that I cannot identify: "gssd", "gsst", "gstd" and "gspu" are some of them.

I know of keys defined for iTunes (in AtomicParsley's website there is some info), but those won't appear in the .mp4 files I have analyzed with a hex editor. Instead I find these not-telling-me-anything keys. Their values are also not very representative: their type is text and they look like "0", "300953" or "B4A7D6381HH"

1 Answer
1

I did a little test of my own. I took a video I uploaded to vimeo and checked the metadata using MediaInfo. It did not contain any of the tags gsst, gstd, gssd, gshh in the general section or any other section.

Next I uploaded the downloaded Vimeo video to YouTube. I proceeded to download the video once again and checked the meta tags. Turns out the meta tags were present.

Using Chrome's Developer tools > Resources it looks like gshh points to the XHR videoplayback. It's the direct link in the page and seems to be embedded in the file. I couldn't determine what the others store.

Minor Update

I went back today and used Youtube's editing capabilities to add a filter to my video. I downloaded the video and some of the values changed.

The superuser question noted that some of these values change. In this instance, same video with an edit performed via Youtube, only gstd and gssd changed. I thought gssd might be a hash, but I found no evidence to support this idea.